Servo Tester Using Picaxe 08M
| Attachment | Size |
|---|---|
| servopot4.bas | 3.23 KB |
| servotst.png | 4.71 KB |
This is my second Picaxe project . It is a simple servo tester or servo cycler built using an 08M . It has 3 modes of operation . In mode 1 each servo is controlled by its own pot . In mode 2 both servos are centered with a 1.5 millisecond pulse . In mode 3 both servos are cycled with the left pot setting the low end point and the right pot setting the high end point . The modes are cycled using a normally open switch . I had to use the pulseout command instead of the servo and servopos commands to avoid jitter .
I used an enclosure from an old rc toy airplane charger for the case . It was a tight fit for the 4 AA battery box , 2 pots , circuit board etc. The circuit board was made by laser printing onto a label backing sheet and transferring by iron to the pcb . Ferric chloride was used for etching . This was the first time I tried the laser printer method and the results were ok but not great .
I know you can buy a single channel version of this for a few dollars but I like to make my own stuff . It's really handy for setting up servos without doing any programming . I have included the basic program and schematic for anyone who is interested .
@ Thu, 2011-09-22 01:31
I´ll be DAMNED!
Hey Rick100,
I took the liberty of copying your code provided in this post and stripping it out to the bare minimum. I ended up with this:
#picaxe 18x
symbol potvaluex = w3
symbol potvaluey = w4
setfreq m8 'run @ 8 MHz for twice servo resolution
pause 2000
low 4 'initial state of servo signal lines
low 5
main:
readadc10 0,potvaluex ' 'read 10 bit value into potvalue
potvaluex = potvaluex * 5 / 17
potvaluex = potvaluex + 150
pulsout 4,potvaluex
pause 50
readadc10 1,potvaluey ' 'read 10 bit value into potvalue
potvaluey = potvaluey * 5 / 17
potvaluey = potvaluey + 150
pulsout 5,potvaluey
pause 50
goto main
I get the same jitter as before. Do you have any idea why this is not working for me when it clearly works for you?
Thanks,
Andrés
@ Thu, 2011-09-22 04:26
I would delete the first
I would delete the first 'pause 50' and change the second one to 'pause 25' but I don't think that's your problem . Is the circuit built on a breadboard ? Have you tried adding a 100 or 220 uF cap where the power supply comes onto the board ? Measure voltages while its running . Try measuring voltage from where ground enters the board to the ground pin on the picaxe and the ground pins of the servos in case you have a bad connection . Do this for the positive voltage also .If the connections are good the voltage reading should be be close to zero . While it's running , push on the connections . Whenever I have any kind of erratic behaviour , I always look for bad connections . You can also try the following code that does't read the pots to try and isolate the problem . It just sets the servos to center position .
#picaxe 18x
symbol potvaluex = w3
symbol potvaluey = w4
setfreq m8 'run @ 8 MHz for twice servo resolution
pause 2000
low 4 'initial state of servo signal lines
low 5
main:
pulsout 4,300
pulsout 5,300
pause 30
goto main
It's an edited version of your code and I haven't tested it .
Good luck and let me know how it goes .
Rick
@ Sun, 2011-09-18 01:47
JOY!
Hey Rick100,
I have experimented with something similar, but with the pots placed on a joystick: PIC-AIM. I struggled with it for a month with no success. Servo jitter was my enemy. The funny thing is that I have collected this page of yours before I started that experiment. It looks as though the answer to my problem has been in "My Collection" all along. I´ve taken a look at your code and your pulseout approach looks promising. I can´t wait to adapt it to my gizmo.
For some reason I remembered this project of yours today...
Andrés
@ Sun, 2011-08-28 22:36
'serfreq' command not supported
I'm using a Stamp board to compile Servopot4.bas and Im getting th following error: 'serfreq' command not supported in this mode, does it mean I have to get a Picaxe 08M in order to run Servopot4.bas?
http://i1204.photobucket.com/albums/bb407/cncfreakcncfreak/Picaxe%20projects/DSC03657.jpg
http://s1204.photobucket.com/albums/bb407/cncfreakcncfreak/Picaxe%20projects/?action=view¤t=DSC03656.jpg
@ Mon, 2011-08-29 22:17
I am not familer with your
I am not familer with your Stamp board . Is it the original Parallax Basic Stamp , also called the Stamp 1 ? The program will not run on a Parallax Stamp . It will run on an Picaxe 08M without change . I haven't tried it yet on an 08M2 . I have some ordered and will post any code updates as soon as I can .
Good luck.
@ Sat, 2011-07-09 01:16
Cheaper servo tester
@ Mon, 2011-06-06 17:44
Very handy tool my friend. I
Very handy tool my friend. I also like food containers too,easy to make them waterproof also. Thanks for sharing :)
@ Sun, 2011-06-05 15:14
Thanks for sharing!
I have built myself one few months ago. Mine is very simple comparing to yours, it just controls 2 servos with 2 pots. And it is very bulky as I've used my favorite enclosure - lunch box :) I believe this device is a MUST HAVE for a robot hobbyist, and as you have said, preferrably DIY. Thanks a lot for posting! Ah, here is mine:
@ Sun, 2011-06-05 17:15
What processor did you use
What processor did you use or did you use a 555 timer . I like food containers as enclosures also . Here is a picture of my FTDI breakout board with a Picaxe programming jack .
@ Sun, 2011-06-05 18:06
Same as you did. 08M rocks!
Same as you did. 08M rocks! :)